This invention relates to telephone devices, especially devices such as telephone answering machines (TADS) and telephone recording devices (TRDs) wherein some signal or conversation is being recorded off the telephone line and some sort of "timestamp" to document the time (and/or day or day-and-date) is often desirable. The preferred apparatus of the invention is embodied to serve this need most concisely by responding automatically to an audio-frequency signal of fixed duration, bandpass and amplitude characteristics typical of the "beep" produced on the telephone line by most TADs at the start of on-line recording, and thereafter using a voice-capable integrated circuit (IC or "chip") to apply an audible timestamp to the telephone line. This timestamp will obviously be recorded by the TAD producing the "beep", thereby producing a suitable audible marker for the user upon playback, making the invention suitable, for instance, for post-equipping a non-timestamp-capable TAD with the function. Additionally, many timestamp-capable TADs place their signals on the recording tape in a digital form designed to be diecoded by the TAD on playback and reproduced in audio or visual form by the TAD, making such timestamps unuseful if the TAD tape is played back on a different device, such as a tape-player. By providing a direct audio timestamp to the tape, the invention circumvents this for users to whom it may be important.
Over the past years great strides have been made in voice-synthesis technology, and many present-day products and systems use it in some form. Many microprocessors and dedicated IC-circuits capable of voice-synthesis are available, either with "custom" (i.e., designer-specified) or "off-the shelf" (i.e., manufacturer-specified) vocabularies. Most such microprocessors are also, with suitable timing means (e.g., a crystal producing a "time-keeping" frequency such as 32.768 KHz or 7.3728 MHz), capable of maintaining the time, day-of-week and calendar functions for the device, and many dedicated "clock" and "clock/calendar" ICs are similarly available. Likewise, there are many microprocessors and ICs capable of performing the timing and Analog-to-Digital functions for determining the duration, amplitude, bandpass and frequency characteristics of a telephone line signal, although such signals can as easily (as shown in the embodiments herein) be detected and decoded by less complex dedicated circuitry. Thus, as one will understand, a wide variety of such technologies is available to the present-day systems-designer for implementing the voice-synthesis and other functions desirable to the invention, and the prior art is cognizant of many techniques and applications thereof.
It is understood, of course, that there are many millions of non-timestamp-capable TADs in use throughout the world, and any technique which enables the user to cost-effectively postequip such a TAD with timestamp capability will enhance the usefullness and prolong the service life of such devices for users who find the capability retrospectively desirable. Additionally, since it is obviously possible to combine a "manual" or "pushbutton" timestamp application along with such automatic "beep" responses, such a device would also be convenient to users of TRDs (such as detectives and insurance claims agents) who spend a good deal of their time recording important conversations for legal reasons. Lastly, since an external speaker could easily be interfaced to such a device along with a telephone audio interface, such a device could obviously function as a more traditional "talking clock" along with its primary functions.
The apparatus and methods to be described enable audio timestamp information to be passed to a variety of recording devices both automatically and manually. Numerous examples of appropriate technology are readily available in independent forms well known to the state of the art, and they can be married in a wide variety of ways to accomplish the precepts of the invention.